WO2010109965A1

WO2010109965A1 - Resin molded article for optical element, method for manufacturing resin molded article for optical element, device for manufacturing resin molded article for optical element, and scanning optical device

Info

Publication number: WO2010109965A1
Application number: PCT/JP2010/051947
Authority: WO
Inventors: 新一朗原; 利行真島; 安弘松本
Original assignee: コニカミノルタオプト株式会社
Priority date: 2009-03-27
Filing date: 2010-02-10
Publication date: 2010-09-30
Also published as: EP2412507A4; US20120008183A1; KR20120002573A; CN102361738B; JPWO2010109965A1; EP2412507A1; CN102361738A; JP5664546B2

Abstract

Provided is: a resin molded article for an optical element wherein high surface precision is kept since an abnormal appearance-formed portion such as a hesitation mark is effectively formed outside an optical surface without cutting off the portion and an optical surface itself can be less likely to be influenced by shrinkage with hardening such as sink; a method and device for manufacturing the same; and a scanning optical device. The resin molded article for an optical element which comprises first surface portion at a part of the surface of a resin molded base and comprises a hollow portion formed by injecting a fluid into the inside of the base from the outside. Assuming that the distance between the first end of the base and an end of the first surface portion, the end being close to the first end, is A and the distance between the second end of the base, the end being other than the first end and being on the opposite side across the first surface portion, and the end of the first surface portion, the end being on the side close to the second end, is B, the relations of (A>0, B>0, A≤B) are satisfied.

Description

Optical element resin molded article, optical element resin molded article manufacturing method, optical element resin molded article manufacturing apparatus, and scanning optical apparatus

The present invention relates to a resin molded product for an optical element, a method for manufacturing a resin molded product for an optical element, a manufacturing apparatus for a resin molded product for an optical element, and a scanning optical device, and in particular, in a resin filled in a cavity of a mold. The present invention relates to a resin molded product for an optical element in which a hollow portion is formed by injecting a fluid into the liquid, a method for manufacturing a resin molded product for an optical element, a manufacturing apparatus for a resin molded product for an optical element, and a scanning optical device.

These optical elements are generally known to be made of glass, metal, or ceramic. In recent years, those made of resin are used from the viewpoint of ease of molding, freedom of design, or cost reduction. It has come to be used.

These optical elements can be used in a wide variety of applications. As an example, a device that records and reproduces the light emitted from the light source by condensing the light emitted from the light source to form an image on a recording surface, for example, optical information recording A reproduction device, an optical scanning device, and the like are well known. However, such an apparatus has been required to further increase the recording density or the like due to the recent demand for higher image quality and higher definition. However, in order to achieve such high definition, high control and accuracy of each component to be used are required, and even when the optical element is one of the components, the light emitted from the light source is transmitted and reflected. Therefore, higher surface accuracy of the optical surface is required for condensing, deflecting, and deforming. Particularly recently, attention has been focused on short-wavelength blue lasers that can provide a long life and stable output, and as a result, even finer spots can be formed. Accordingly, there has been a demand for optical elements having high surface accuracy corresponding thereto.

However, as the surface accuracy required in this way is increasing, points that have not been so much of concern in the past have become a major technical issue. The most important problem is the influence of deformation of the optical surface due to warpage and sink caused by shrinkage during resin curing in resin injection molding. In particular, in an optical element having an fθ characteristic, the influence of warpage generated in the scanning direction becomes more prominent, and it is difficult to ensure the quality of such a high-precision optical component by conventional injection molding. It has become a situation. Further, as described above, when the laser beam is applied with a short wavelength, for example, a blue laser, the weather resistance of the resin lens becomes a further obstacle to maintaining high surface accuracy.

In response to this problem, the present inventor considered the effect of hollow injection molding and considered application to optical components. By forming into a hollow by hollow injection molding, the tensile stress at the time of resin shrinkage that causes warping and sink marks of the molded product is released to the hollow part, and the molded product is expressed in the form of sink marks on the surface of the hollow part. This is because warpage and sink marks generated on the surface of the film can be alleviated.

Here, as a method of providing a hollow portion in the resin molded product, molten resin is injected and filled into a mold, and then a compressed gas as a fluid is injected from an injection nozzle or a gas injection nozzle provided in a cavity of the mold. In addition, there is a method of obtaining a hollow molded article by using the injected gas. However, since there is a time lag in the gas injection after filling the resin in this way, the flow rate at the tip of the molten resin changes, and in some cases stops, the appearance of hesitation marks etc. on the surface of the tip of the molten resin Abnormality occurs and surface accuracy is significantly reduced.

On the other hand, in the conventional technique (for example, Patent Document 1), the resin is filled from the injection nozzle, and the compressed gas is injected from a different gate in a substantially filled state. At that time, excess resin flows out from the resin outflow path to the outflow resin receiving portion. A detection device detects that the gas has reached a predetermined position before reaching the resin outflow passage, and manufactures a molded product that solidifies the resin in a pressurized state by closing the resin outflow passage with an opening / closing device. Thereafter, the resin outflow path and the outflow resin receiving portion are cut in the mold by the opening / closing member. It is shown that appearance abnormalities such as hesitation marks do not occur.

Japanese Patent Laid-Open No. 11-138777

However, in this prior art, a resin outflow passage and an outflow resin receiving portion, which are unnecessary parts as a resin molded product, are provided, and a portion where an abnormality in appearance such as a hesitation mark is generated is compressed after the resin comes to the outflow passage. It is constructed by forming an abnormal appearance part in an unnecessary molding part outside the cut part and then cutting at the cut part. However, such an unnecessary cut after molding is a scanning optical element having an optical surface that requires high surface accuracy at the periphery of the cut, particularly for performing high-density recording and reproduction using short-wavelength light. It was found that application to optical elements is difficult. In addition, in the case of optical elements, there are technical obstacles that must be solved in conjunction with the generation of hesitation marks.

In the case of an optical element, an optical surface formed on a part of a substrate needs to surely eliminate the problems caused by the curing shrinkage of the resin as described above. It needs to be controlled to some extent below. This means that since the hollow region is formed by injecting fluid into the cavity during molding, it is necessary to anticipate in advance the region where the filled resin is pushed by the fluid. However, unlike other molded parts, optical parts also have limitations because they affect the surface accuracy depending on the resin filling position and fluid injection position. Therefore, it is considered that the resin filling position and injection position are preferably injected from one end of the cavity outside the region where the optical surface is formed.

Therefore, even if resin is filled from such a restricted position and fluid is injected, a hollow region is formed to some extent below the optical surface, and an abnormal appearance forming site such as a hesitation mark does not affect the optical surface. Therefore, it is necessary to consider the shape of the optical component.

The present invention solves the above-mentioned problems, and for this purpose, for optical elements that can effectively solve the problem of surface accuracy degradation due to problems such as sink marks due to resin curing shrinkage and appearance abnormality formation sites such as hesitation marks. An object of the present invention is to provide a resin molded product, a manufacturing method thereof, a manufacturing apparatus, and a scanning optical apparatus.

In order to solve the above-mentioned problem, the first embodiment of the present invention has a first surface portion on a part of the surface of a base material molded from resin, and injects fluid into the base material from the outside. A resin molded article for an optical element having a formed hollow portion, wherein the distance between the first end portion of the substrate and the end portion of the first surface portion on the side close to the first end portion is A, It is an end different from the first end of the base material, the second end on the opposite side through the first surface, and the first surface on the side close to the second end When the distance from the end of the part is B, the resin molded product for an optical element satisfies the following relationship.

A> 0
B> 0
A ≦ B
The second aspect of the present invention is the resin molded product for an optical element according to the first aspect, wherein the surface roughness Ra of the entire first surface portion is Ra ≦ 5 (nm). Features.

Furthermore, a third aspect of the present invention is a resin molded product for an optical element according to the first aspect, wherein a mirror surface portion is formed on the first surface portion.

Furthermore, a fourth aspect of the present invention is a light source, a deflecting unit for deflecting the emitted light emitted from the light source, a condensing unit for allowing the light emitted from the light source to be incident and condensed on the deflecting unit, A scanning optical device having an imaging optical system for imaging light deflected by the deflecting means on the surface to be scanned, wherein at least one of the optical elements constituting the imaging optical system is made of resin. An optical element having one surface part on a part of the surface of a long shaped base material and having a hollow part formed by injecting a fluid from the outside into the base material. A distance between the first end portion of the first surface portion and the end portion of the first surface portion on the side close to the first end portion is an end portion different from the first end portion of the base material, and A second end portion on the opposite side via the surface portion and an end portion of the first surface portion on the side close to the second end portion When the distance was set to B, and the scanning optical apparatus which satisfy the following relationship.

A> 0
B> 0
A ≦ B
Furthermore, a fifth aspect of the present invention is the scanning optical apparatus according to the fourth aspect, characterized in that a surface roughness Ra of the entire first surface portion is Ra ≦ 5 (nm). .

Furthermore, a sixth aspect of the present invention is the scanning optical device according to the fourth or fifth aspect, wherein a mirror surface portion that reflects incident light is formed on the first surface portion. To do.

Furthermore, a seventh aspect of the present invention is the scanning optical apparatus according to the sixth aspect, characterized in that the surface roughness Ra of the mirror surface portion is Ra ≦ 5 (nm).

Furthermore, according to an eighth aspect of the present invention, there is provided a hollow portion having a first surface portion on a part of a surface of a base material formed of a resin and injecting a fluid from the outside into the base material. A distance between the first end of the base and the end of the first surface near the first end is A, and the first of the base An end portion different from the first end portion, the second end portion on the opposite side through the first surface portion, and the end portion of the first surface portion on the side close to the second end portion When the distance of B is B, the following relation A> 0
B> 0
A ≦ B
And a first mold having a transfer surface for transferring the first surface portion, the first mold being provided opposite to the first mold. A second mold for forming a cavity by clamping the mold with the mold, an injection process for injecting molten resin into the cavity from one side of the end of the cavity, and filling by the injection process A detecting step for detecting that the tip of the resin is in a predetermined position, and controlling filling of the filled resin based on detection of the detecting step, and injecting fluid into the cavity And a fluid injection step of forming a hollow portion in the manufacturing method of a resin molded product for an optical element.

Furthermore, a ninth aspect of the present invention is a method for producing a resin molded product for an optical element according to the eighth aspect, wherein the surface roughness Ra of the first surface portion is Ra ≦ 5. And

Furthermore, the 10th form of this invention is the manufacturing method of the resin molded product for optical elements which concerns on the said 8th or 9th form, Comprising: The 1st surface part of the resin molded product obtained after the said fluid injection | pouring process And a mirror surface portion forming step of forming a mirror surface portion.

Furthermore, an eleventh aspect of the present invention is a method for manufacturing a resin molded product for an optical element according to any one of the eighth to tenth aspects, wherein the fluid injection step is performed for a predetermined time after stopping the resin filling. The fluid injection is started after the passage.

Furthermore, the twelfth aspect of the present invention is a hollow part formed by injecting a fluid from the outside into the base material having a first surface part on a part of the surface of the base material formed of resin. A distance between the first end of the base and the end of the first surface near the first end is A, and the first of the base An end portion different from the first end portion, the second end portion on the opposite side through the first surface portion, and the end portion of the first surface portion on the side close to the second end portion When the distance of B is B, the following relation A> 0
B> 0
A ≦ B
An apparatus for manufacturing a resin molded product for an optical element satisfying the first mold, provided with a first mold having a transfer surface for transferring the first surface portion, facing the first mold, and the first mold A second mold for forming a cavity by clamping between the mold, a filling means for injecting a molten resin material into the cavity from one side of the end of the cavity, and filling the cavity with the filling means Detecting means for detecting that the resin is in a predetermined position; fluid injecting means for injecting a fluid into the cavity to form a hollow portion therein; and the resin is filled in the predetermined position by the detecting means. And a control means for controlling the filling of the resin by the filling means and the injection of the fluid into the cavity by the fluid injecting means. It is a device.

According to the present invention, an abnormal appearance forming portion such as a hesitation mark is effectively formed outside the optical surface without being removed by cutting, and the optical surface itself is affected by curing shrinkage such as sink marks. Therefore, it is possible to provide a resin molded product for an optical element that maintains high surface accuracy, and a manufacturing method, a manufacturing apparatus, and a scanning optical apparatus for manufacturing the same.

It is explanatory drawing of the laser beam scanning optical apparatus incorporating the optical element which concerns on 1st Embodiment of this invention. It is sectional drawing which sheared and showed the resin molded product for optical elements in the elongate direction. It is a top view of the resin molded product for optical elements. (A) is sectional drawing of the metal mold | die at the time of cut | disconnecting by the perpendicular surface containing the bisector of a short length direction, (b) is the metal at the time of cut | disconnecting by the perpendicular surface containing a bisector of a long direction It is sectional drawing of a type | mold. It is a functional block diagram of the injection molding machine provided with the detection means. It is a time chart which shows the relationship between detection temperature and injection | pouring of compressed gas. It is a flowchart which shows the manufacturing process of the resin molded product for optical elements. It is a functional block diagram of the injection molding machine which concerns on a modification. It is a time chart which shows the relationship between detection temperature and injection | pouring of compressed gas. It is a flowchart which shows the manufacturing process of the resin molded product for optical elements which concerns on a modification. It is a functional block diagram of the injection molding machine which concerns on another modification. It is a flowchart which shows the manufacturing process of the resin molded product for optical elements which concerns on another modification. It is a top view of the resin molded product for optical elements which concerns on 2nd Embodiment of this invention. It is a cross-sectional view of the resin molded product for optical elements.

[First Embodiment]
(Constitution)
A resin molded product for an optical element according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an example of a laser beam scanning optical apparatus in which a resin molded product for an optical element is incorporated.

In FIG. 1, a laser beam scanning optical device includes a light source unit 1, a cylindrical mirror 2, a polygon mirror 3 as a deflecting means, a toric lens 4, planar mirrors 5 and 6, and an fθ mirror 10 having fθ characteristics. It consists of

The laser beam emitted from the light source unit 1 is converged into substantially parallel light by a collimator lens (not shown), and then reflected by a cylindrical mirror 2, and the beam shape is substantially linear with the long direction parallel to the main scanning direction. And the polygon mirror 3 is reached.

The polygon mirror 3 has four deflection surfaces on its outer peripheral surface and is driven to rotate at a constant speed in the counterclockwise direction. The laser beam is deflected at a constant angular velocity in the main scanning direction by the rotation of the polygon mirror 3, and when guided to the toric lens 4, the toric lens 4 has different powers in the main scanning direction and the sub scanning direction. By converging the laser beam on the surface to be scanned, the deflection surface of the polygon mirror 3 and the surface to be scanned are kept in a conjugate relationship, and the surface tilt error of each deflection surface of the polygon mirror 3 is obtained by combining with the cylindrical mirror 2. Correct.

In addition, although the polygon mirror was demonstrated as an example here as a deflection | deviation means, it does not specifically limit. That is, it is only necessary that incident light can be deflected in another direction, and it is needless to say that other known deflecting means such as a galvanometer mirror can be adopted.

The laser beam that has passed through the toric lens 4 is reflected by the plane mirrors 5 and 6, further reflected by the fθ mirror 10, and then condensed on the photosensitive drum 7. The fθ mirror 10 converts the speed of the laser beam deflected at a constant angular velocity by the polygon mirror 3 so that the linear velocity is constant on the scanning surface (on the photosensitive drum 7). The photosensitive drum 7 is rotationally driven counterclockwise at a constant speed, and the photosensitive drum 7 is driven based on the main scanning of the laser beam by the polygon mirror 3, the rotation of the photosensitive drum 7 (sub scanning), and the modulated laser beam output. An image is formed on top.

As described above, the laser beam scanning optical apparatus is composed of various optical elements. In particular, the base materials such as the flat mirrors 5 and 6 and the fθ mirror 10 are formed in a long plate shape, provided with a mirror surface that reflects a laser beam received within a predetermined range in the longitudinal direction, and is photosensitive. Since an image is formed on the body drum 7, the accuracy of the surface of the optical element provided with a mirror surface directly affects the image quality.

Next, the detailed structure of the resin molded product for an optical element will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing the resin molded product for optical elements sheared in the longitudinal direction, and FIG. 3 is a plan view of the resin molded product for optical elements.

Optical elements are strongly required to have specularity, dimensional accuracy, lightness, safety, durability, and economy. It is an optical element suitable for many uses such as electric and electronic parts, automobile parts, medical use, security use, building materials, and household goods.

As an example of the optical element according to the present invention, as described above, the plane mirrors 5 and 6 and the fθ mirror 10 incorporated in the laser printer can be cited. Each substrate of the plane mirrors 5 and 6 and the fθ mirror 10 has a hollow portion, and a hesitation mark is provided outside the surface with high surface accuracy. Hereinafter, the fθ mirror 10 will be described as a representative, and description of the plane mirrors 5 and 6 and other optical elements will be omitted.

The fθ mirror 10 is formed in a long plate shape, has a predetermined range H1 in the longitudinal direction, and is provided with a first surface portion 11 provided with a mirror surface portion 13 that reflects a light beam received within the predetermined range H1. And a pair of second surface portions 12 arranged so as to sandwich the first surface portion 11 from the longitudinal direction. Note that the horizontal direction toward the plane of FIG. 2 is the long direction, the vertical direction is the thickness direction, and the vertical direction in FIG. 3 is the short direction.

In the width in the longitudinal direction, the predetermined range H1 is set to be equal to or less than the area of the mirror surface portion 13, and the area of the mirror surface portion 13 is set to be equal to or less than the area of the first surface portion 11. In addition, the area | region of the mirror surface part 13 and the area | region of the 1st surface part 11 made to correspond by the width | variety of a elongate direction are shown in FIG.

The fθ mirror 10 has a long plate-like base material, a mirror surface portion 13 located on one surface of the base material, and a hollow portion 14 located inside the base material on the mirror back surface of the mirror surface portion 13. And the length of the longitudinal direction of the hollow part 14 is longer than the length of the longitudinal direction of the mirror surface part 13, Furthermore, both ends of the hollow part 14 are formed outside the both ends of the longitudinal direction of the mirror surface part 13. Since the tensile stress generated by the shrinkage accompanying the curing of the resin is released to the hollow portion 14, warpage in the longitudinal direction due to the resin shrinkage is alleviated over the entire mirror surface portion 13 and the surface accuracy is improved.

In the prior art, the mold is held by the molded product due to the resin shrinkage, and the mirror surface portion 13 is distorted due to the mold release resistance. It is possible to suppress the occurrence of distortion of the mirror surface portion 13 due to the mold release resistance. Further, when the optical element (resin molded product) is manufactured, the shape of the mirror surface portion 13 is changed by correcting the mirror surface portion 13, for example, correcting the thickness of the mirror surface portion 13 partially or entirely in the thickness direction. There is a case. Even when the plate surface of the mirror surface portion 13 is buried in the base material as a result of the correction, the amount of correction of the mirror surface portion 13 is anticipated and the length by which the mirror surface portion 13 protrudes from the base material is adjusted in advance. After that, it is possible to adjust so that the plate surface of the mirror surface portion 13 protrudes on the plate surface of the substrate, and as a result, it is possible to avoid holding the mold by the molded product.

In the resin molded product of the present embodiment, the length in the long direction of the mirror surface portion 13 is L1, the length in the short direction is W1, the length in the long direction of the hollow portion 14 is L2, and the length in the short direction is W2. When the length in the thickness direction is D2, the length in the short direction of the substrate is W4, and the distance from the end of the mirror surface portion 13 to the end of the substrate is L5 with respect to one side in the long direction, one side in the long direction On the other hand, the distance L3 from the end of the mirror surface portion 13 to the end of the hollow portion 14 is 0 ≦ L3 <L5, and the distance W3 from the end of the mirror surface portion 13 to the end of the hollow portion 14 is 0 ≦ W3 with respect to one side in the short direction. It is more preferable to configure so as to satisfy <W2 / 2.

Also, the distance from the end of the optical element on the same side as the end of the first surface portion 11 is A, and is an end different from the end of the first surface 11 and is opposite via the hollow portion 14 When the distance between the end of the first surface portion 11 formed on the side and the end of the optical element on the same side is B, the optical element shape is such that A> 0 and B> 0. is necessary.

In addition, at this time, when resin is filled from the resin filling end J on the A side and fluid is injected, A ≦ B (A ≧ B when resin is filled from the B side and fluid is injected) It is necessary to reliably drive the appearance abnormality formation site such as hesitation out of the first surface portion 11 and to form the hollow portion 14 below the region corresponding to the first surface portion 11.

In the case of a small optical element, A and B are 3.5 ≦ A ≦ 5.0 and 3.5 ≦ B ≦ 5.0, and it is more preferable to satisfy the above-described conditions.

Further, when the length in the thickness direction of the mirror surface portion 13 protruding from the plate surface of the base material is D1, D1 is 0.1 (mm) <D1 ≦ 3 (mm). Since the side area of the portion 13 increases, the mold release resistance increases, and the surrounding mirror surface accuracy decreases, it is preferable that 0.1 (mm) <D1 ≦ 0.3 (mm) is satisfied.

In addition, the relationship between the length W1 of the mirror surface portion 13 and the length W2 of the hollow portion 14 in the short direction is preferably 0.01 ≦ W2 / W1 ≦ 1.

In FIG. 1 and FIG. 2, the hollow portion 14 is arranged in the center in both the short direction and the thickness direction, and is described in a straight line shape parallel to the mirror surface portion 13, but this is merely a schematic example. However, the shape and positional relationship of the hollow portion 14 are not limited.

A hesitation mark HM is formed on the second surface portion 12. The hesitation mark HM may be formed anywhere within the width of the second surface portion 12 in the longitudinal direction, but is preferably formed as far away as possible from the first surface portion 11.

In the first embodiment, the fθ mirror 10 is shown as a resin molded product for an optical element formed in a long plate shape. However, if the resin molded product for an optical element formed in a plate shape is used, it is long. Not limited to scales. It may be circular, elliptical, or substantially square. In this case, the hollow portion 14 may be formed along the first surface portion 11 and wider than the first surface portion in the aligned direction.
(Injection molding machine)
Next, an injection molding machine for manufacturing the base material of the fθ mirror 10 will be described with reference to FIGS. 4A is a cross-sectional view of a mold when cut along a vertical plane including a bisector in a short direction, and FIG. 4B is a cross section along a vertical plane including a bisector in a long direction. FIG. 5 is a functional block diagram of an injection molding machine provided with the detecting means 33, and FIG. 6 is a time chart showing the relationship between the detected temperature and the injection of compressed gas.

The injection molding machine includes a mold 42 having a cavity 31, filling means 32 for filling the cavity 31 with resin, detection means 33 for detecting the tip of the resin, and injecting compressed gas into the filled resin. Gas injection means 34 for controlling, filling of resin, stopping of filling of resin, and control means 35 for controlling start of injection of compressed gas and stop of injection of compressed gas.
(Mold)
The cavity 31 has an inner surface for forming the first surface portion 11 and the second surface portion 12 constituting the outer surface of the optical element resin molded product. Here, the shape of the mold will be described with reference to FIG. 4A is a cross-sectional view of a mold cut along a vertical plane including a bisector in the short direction, and FIG. 4B is a vertical plane including a bisector in the long direction. It is sectional drawing of the metal mold | die at the time of cut | disconnecting by. The inner surface of the cavity 31 has a first region 311 for forming the first surface portion 11 and a second region 312 for forming the second surface portion 12. In FIG. 4, the distance between the end of the cavity on the resin filling side and the fluid injection side and the end of the first surface portion 11 is A, and the distance between the other end and the end of the first surface portion 11 is B. Show.

Here, the mirror surface forming portion 315 is cut to a surface roughness Ra of 5 nm or less in order to achieve surface accuracy used for short wavelengths of, for example, a wavelength of 500 nm or less. The surface roughness Ra is more preferably 2 to 3 nm or less.

Further, the configuration around the mold in the injection molding machine will be described with reference to FIG. In the cavity 31, a gate 321, a runner 322, and a spool 323 are continuously formed. A heater (not shown) is provided along the cavity 31, and the runner 322 and the spool 323 (the passage of the mold). By providing the heater, the molten resin in contact with the cavity 31 and the mold passage is cooled by heat conduction and prevented from losing fluidity and solidifying. Instead of the heater, a temperature adjusting water channel may be provided in the mold. The inner surface of the cavity 31 is shown in FIG. 5 as the outer shape of the fθ mirror (resin molded product) 10 filled in the cavity 31, and the gate 321, the runner 322, and the spool 323 are similarly passed through these parts. The outer shape of the resin is shown in FIG.
(Filling means)
The filling means 32 is preferably arranged in the mold so as to be filled from the short side of the fθ mirror 10 toward the long direction. FIG. 5 shows the short side of the fθ mirror 10 as the right end side of the cavity 31.

A nozzle 324 of the filling means 32 communicates with the spool 323. The filling means 32 has a screw (not shown) for extruding the molten resin from the nozzle 324. The screw passes the molten resin from the nozzle 324 through the spool 323, the runner 322, and the gate 321 and fills the cavity 31. The distance from the screw movement start position or the elapsed time from the screw movement start corresponds to the amount of extruded molten resin (injection amount). Further, since the volume of the mold passage from the spool 323 to the gate 321 and the cross-sectional shape of the cavity 31 at each position in the longitudinal direction are known, the distance from the screw movement start position or the screw Based on the elapsed time from the start of the movement, the position of the tip of the molten resin filled in the cavity 31 can be obtained.
(Detection means)
The detection means 33 is a temperature sensor that detects the temperature of the inner surface of the cavity 31. One or a plurality of detection means 33 includes the second region 312 on the inner surface of the cavity 31 for forming the second surface portion 12, and the cavity 31 has the same range as the second region 312 in the longitudinal direction. Arranged on the inner surface. Here, the inner surface of the cavity 31 having the same range as the range of the second region 312 in the longitudinal direction is the inner surface of the cavity 31 that circulates in the same range as the range of the second region 312 in the longitudinal direction. When the second region 312 is a ceiling surface, the bottom surface 313 and the side wall surfaces 314 are provided. FIG. 5 shows the detection means 33 disposed on the bottom surface 313 facing the second region 312 (ceiling surface) opposite to the gate-side second region 312 in the longitudinal direction. The detection means 33 is not limited to a temperature sensor as long as it is a sensor that can detect the tip of the resin at the time of injection in the cavity 31. For example, an ultrasonic sensor or a magnetic sensor may be used. .

The detection means 33 can detect the tip of the resin that has reached the second region 312 of the cavity 31. The control means 35 receives a detection temperature t1 which is a detection signal from the detection means 33 via the interface 38. The control means 35 controls the filling means 32 based on the detected temperature t1 from the detection means 33, stops the resin filling, controls the gas injection means 34, and starts the injection of the compressed gas.

By providing the detection means 33 on the inner surface of the cavity 31 that includes the second region 312 and has the same range as the range of the second region 312 in the longitudinal direction, the detection means 33 is provided on the surface of the first surface portion 11. It does not cause a decrease in accuracy. In addition, the detection means 33 directly detects the tip of the resin that has reached the second region 312, receives the detection signal, stops the filling of the resin, and starts the injection of the compressed gas. After the portion reaches the second region 312, the filling of the resin is stopped, and there is little time error from the start of the injection of the compressed gas, and the hesitation mark HM is reliably formed on the second surface portion 12. It becomes possible to prevent the surface accuracy of the surface portion 11 from being lowered.
(Gas injection means)
The gas injection means 34 has a tank (not shown) in which compressed gas is stored, an electromagnetic valve 341, and an injection port 342 that communicates with the cavity 31. The control means 35 controls opening and closing of the electromagnetic valve 341. The compressed gas to be used may be any gas that does not react or mix with the resin. For example, an inert gas is mentioned. In view of safety and cost, nitrogen is preferable because it is nonflammable and toxic, and can be obtained by an inexpensive method. The injection port portion 342 is a region corresponding to the second region 312 on the inner surface of the cavity 31 and is provided on the bottom surface 313. That is, it is provided on the bottom surface in the space between the first surface portion end and the position corresponding to the optical element end.
(Memory means)
The storage means 36 stores a predetermined reference temperature t0 to be compared with the detected temperature t1 from the detection means 33. The detected temperature t1 and the reference temperature t0 are shown in FIG.
(Judgment means)
The determination unit 37 compares the detected temperature t1 with the reference temperature t0, and outputs a determination result to the control unit 35 when the detected temperature t1 exceeds the reference temperature t0. When the tip of the molten resin reaches the position of the detection means 33, the detection temperature t1 detected by the detection means 33 is set as a reference temperature t0.
(Control means)
The control unit 35 receives the detection temperature t1 from the detection unit 33, causes the determination unit 37 to compare the detection temperature and the reference temperature, and when the determination unit 37 determines that the detection temperature t1 exceeds the reference temperature t0, The means 32 is controlled to stop the filling of the resin into the cavity 31, and the gas injection means 34 is controlled to start the injection of the compressed gas into the filled resin. Further, the control means 35 stops the injection of the compressed gas after a predetermined time has elapsed since the start of the injection of the compressed gas. FIG. 6 shows an operation for stopping the filling of the resin and an operation for starting the injection of the compressed gas when the detected temperature t1 exceeds the reference temperature t0.

By injecting compressed gas into the filled resin, the molten resin part forming an abnormal appearance forming part such as hesitation is the second surface part opposite to the injection port part 342 side through the first surface part 11. 12, the resin is pushed into a space formed with a length equal to or longer than that of the injection port 342 side, so that the formed hollow portion 14 has a margin below the region corresponding to the first surface portion 11. It is formed widely throughout. The formed hollow portion 14 can release the influence of tensile stress due to the thermal contraction of the resin, and the warpage of the first surface portion 11 can be reduced.

Further, it is preferable that the hollow portion 14 is formed widely up to the region corresponding to the second surface portion 12 because the warpage of the first surface portion 11 can be more reliably reduced.

In consideration of the fact that the start of the injection of the compressed gas is before the resin cooling proceeds after the resin filling is stopped, it is preferable that the injection of the compressed gas is almost simultaneously with the stop or within 1 to 5 seconds after the resin filling.

When the control means 35 receives an operation by the operation means 41 via the interface 38, the control means 35 adjusts a predetermined time and causes the storage means 36 to store the predetermined time after the adjustment. By adjusting the predetermined time, the position of the hesitation mark HM can be adjusted.

The control unit 35 receives the instruction from the operation unit 41 and stores the changed reference temperature t0 in the storage unit 36. In order to adjust the stop of the filling of the resin and the start of the injection of the compressed gas, the reference temperature t0 may be changed and adjusted. The reference temperature t0 is determined empirically by repeating the manufacturing experiment of the base material of the fθ mirror 10 and measuring and evaluating the manufactured fθ mirror 10. The reference temperature t0 is relatively determined based on the material of the base material of the fθ mirror 10, the temperature of the heating cylinder, and the resin filling amount per unit time.
(Materials for resin molded products for optical elements)
Next, materials for the fθ mirror 10 will be described. Examples of the resin material constituting the base material of the fθ mirror 10 include polycarbonate, polyethylene terephthalate, polymethyl methacrylate, cycloolefin polymer, or a resin composed of two or more of these. In the fθ mirror 10, it is preferable to use a polycarbonate or a cycloolefin polymer.
(Mirror surface material)
Next, the material etc. which comprise the mirror surface part 13 of the f (theta) mirror 10 are demonstrated. Examples of the material constituting the mirror surface portion 13 include silicon monoxide, silicon dioxide, and alumina. As a film forming method, a known film forming method such as a vacuum deposition method, a sputtering method, or an ion plating method can be used.
(Production method)
Next, a method for manufacturing the fθ mirror 10 will be described with reference to FIG. FIG. 7 is a flowchart showing manufacturing steps of the fθ mirror 10.

Before filling the mold cavity 31 with resin, the cylinder (not shown) of the filling means 32 is set to have a predetermined melting temperature. Further, the control means 35 closes the electromagnetic valve 341. The control means 35 controls the filling means 32, rotates the screw, injects the molten resin from the nozzle 324, passes through the spool 323, the runner 322, and the gate 321 and fills the cavity 31 (step S101). .

Further, the cavity 31 is filled with molten resin. The detection means 33 detects the tip of the molten resin that has reached the second surface portion 12. When the determination means 37 determines that the detected temperature t1 detected by the detection means 33 has exceeded the reference temperature t0 (step S102; Y), the control means 35 controls the filling means 32 to stop the filling of the resin into the cavity 31. (Step S103). Next, the control means 35 controls the gas injection means 34 to open the electromagnetic valve 341. Thereby, the compressed gas in the tank (not shown) is ejected from the injection port portion 342 into the cavity 31.

The injection port portion 342 is disposed on the bottom surface 313 facing the second region 312, and the injection port portion 342 is opened in the longitudinal direction, whereby compressed gas is filled in the longitudinal direction in the filled resin. Is injected (step S104). Thereby, the hollow part extended in the elongate direction can be formed in resin. Also, when the tip of the molten resin reaches the second surface portion 12, filling of the resin is stopped and compressed gas is injected into the resin, so that a hesitation mark is formed on the second surface portion 12, Since the first surface portion 11 is not formed, the surface accuracy of the first surface portion 11 is not lowered.

Next, the molten resin is solidified and cooled by heat conduction with the mold. The hollow portion 14 is held at a predetermined pressure until it is solidified and cooled (step S105). By holding the pressure, the first surface portion 11 is pressed against the first region 311, so that the surface transfer property of the first surface portion 11 can be improved. The mirror surface portion 13 is formed on the first surface portion 11 during the compressed gas injection step (step S104) to the pressure holding step (step S105). Next, the compressed gas in the hollow portion 14 is removed, the mold is opened, and the fθ mirror (resin molded product) 10 is taken out (step S106).

In step S102, the control unit 35 receives the detection temperature t1 that is a detection signal from the detection unit 33, and when the determination unit 37 determines that the detection temperature t1 exceeds the reference temperature, the filling of the resin is performed. Stopped and started the injection of compressed gas. As can be seen from the above, the number of detection means 33 provided on the bottom surface 313 and the like (including the side wall surface 314) facing the second region 312 is one. A plurality of detection means 33 may be provided on the bottom surface 313 facing the second region 312 or the like.

When a plurality of detection means 33 are provided, the resin filling is stopped and the compressed gas injection is started as follows. The control means 35 sets in advance whether the control means 35 controls the filling means 32 and the gas injection means 34 when the detection temperature t1 detected by the detection means 33 exceeds the reference temperature t0. Is stored in the storage means 36. When the control temperature 35 detected by the predetermined detection means 33 exceeds the reference temperature t0, the control means 35 controls the filling means 32 to stop the resin filling, and controls the gas injection means 34. Then, the injection start of the compressed gas may be controlled. By providing a plurality of detection means 33, the filling of the resin is stopped, the accuracy of the timing of injecting the compressed gas is improved, and the hesitation mark HM can be reliably formed on the second surface portion 12.

In the first embodiment, the detection unit 33 is provided on the inner surface of the cavity 31 including the second region 312 and having the same range as the second region 312 in the longitudinal direction, and the temperature detected by the detection unit 33 is the reference temperature. In the above description, the control means 35 controls the filling means 32 and the gas injection means 34 when the value exceeds the above.

Next, a manufacturing apparatus according to a modification of the first embodiment will be described with reference to FIGS. FIG. 8 is a functional block diagram of an injection molding machine provided with the detection means 33 and the timer 39, and FIG. 9 is a time chart showing the relationship between the detected temperature and the start of injection of compressed gas. By providing the timer 39, the detection means 33 can be provided in the first region 311.

When the determination unit 37 determines that the detected temperature t1 from the detection unit 33 has exceeded the reference temperature t0, the control unit 35 causes the timer 39 to measure the elapsed time from the time when the detected temperature t1 has exceeded the reference temperature t0. When the determination unit 37 determines that the time has been exceeded, the control unit 35 controls the filling unit 32 to stop the filling of the resin, controls the gas injection unit 34 to start the injection of the compressed gas, and presses the compressed gas. The injection of the compressed gas is stopped after a lapse of a predetermined time from the start of the injection. An operation for counting the elapsed time when the detected temperature t1 exceeds the reference temperature t0, an operation for stopping the filling of the resin when the elapsed time exceeds a predetermined time, and injection of compressed gas. The operation to be started is shown in FIG.

One or a plurality of detection means 33 are arranged on the inner surface of the cavity 31 having the same range as the range of the first region 311 in the longitudinal direction except for the first region 311 for forming the first surface portion 11. Yes. FIG. 8 shows the detection means 33 arranged on the bottom surface 313 facing the first region 311 (ceiling surface). The inner surface of the cavity 31 having the same range as the first region 311 in the longitudinal direction is the bottom surface 313 and both side wall surfaces 314 when the first region 311 is a ceiling surface. Since the detection means 33 is disposed on the bottom surface 313, it does not cause a decrease in the surface accuracy of the first surface portion 11.

When it is estimated that the tip of the molten resin has reached the second region 312 from the first region 311, the control means 35 stops filling the resin and starts injecting compressed gas. As a result, the hesitation mark HM can be formed on the second surface portion 12.

Further, for example, under the limitation of the installation space of the detection means 33 or the limitation of the shape of the fθ mirror 10 (resin molded product), the second region 312 is included and has the same range as the range of the second region 312 in the longitudinal direction. In some cases, the detection means 33 cannot be installed on the inner surface of the cavity 31. In this case, it can be provided on the bottom surface 313 or the side wall surface 314 which is the inner surface of the cavity 31 having the same range as the first region 311 in the longitudinal direction. Thereby, the freedom degree of installation of the detection means 33 can be improved.

Note that the above predetermined time is, for example, from the determination that the determination unit 37 determines that the detection temperature t1 detected by the detection unit 33 has exceeded the reference temperature t0, until the leading end of the resin reaches the second region. Is measured for a predetermined number of times, and the movement of the tip of the resin (spreading in the cavity 31 and movement in the longitudinal direction) is calculated by approximation from the measured value, and obtained based on the calculated result. It's time. The control unit 35 stores the determined predetermined time in the storage unit 36. In response to the operation of the operation unit 41, the control unit 35 adjusts a predetermined time and stores it in the storage unit 36. Thereby, it is possible to reduce an error that occurs between the determined predetermined time and the actual time until the front end of the resin reaches the second region 312.

Furthermore, a plurality of detection means 33 may be provided, and the moving speed in the longitudinal direction of the front end portion of the resin may be obtained based on the detected temperatures t1 from the plurality of detection means 33. In this case, a predetermined time is corrected based on the obtained moving speed, and the corrected predetermined time is stored in the storage means 36. The judging means 37 includes an elapsed time after the judging means 37 judges that the detected temperature t1 has exceeded the reference temperature t0 from the detecting means 33, and the corrected predetermined time (the resin tip is in the second region). Compared to the estimated time to reach The control unit 35 controls the filling unit 32 and the gas injection unit 34 when the determination unit 37 determines that the elapsed time exceeds the corrected predetermined time.

Next, a method for manufacturing the base material of the fθ mirror 10 according to the modification will be described with reference to FIG. FIG. 10 is a flowchart showing the manufacturing process of the base material of the fθ mirror 10.

The control means 35 controls the filling means 32, rotates the screw, injects molten resin from the nozzle 324, passes through the spool 323, the runner 322, and the gate 321 and fills the cavity 31 (step S201). .

Further, the cavity 31 is filled with molten resin. The detection means 33 detects the tip of the molten resin that has reached the first surface portion 11. When the determination unit 37 determines that the detected temperature t1 detected by the detection unit 33 exceeds the reference temperature t0 (step S202; Y), the control unit 35 causes the timer 39 to measure the elapsed time since the determination (step S203). . When the determination means 37 determines that the measured elapsed time has exceeded a predetermined time (step S204; Y), the control means 35 controls the filling means 32 to stop filling the cavity 31 with resin. (Step S205). Next, the control means 35 controls the gas injection means 34 to open the electromagnetic valve 341. Thereby, the compressed gas in the tank (not shown) is ejected from the injection port portion 342 into the cavity 31. At this time, the front end portion of the molten resin reaches the second surface portion 12.

The injection port portion 342 is disposed on the bottom surface 313 facing the second region 312, and the injection port portion 342 is opened in the longitudinal direction, whereby compressed gas is filled in the longitudinal direction in the filled resin. Is injected (step S206). Thereby, the hollow part 14 extended in the elongate direction can be formed in resin. Further, when it is determined that the measured elapsed time has exceeded a predetermined time (when the front end of the molten resin reaches the second surface portion 12), the control means 35 stops filling the resin, Since the compressed gas is injected therein, a hesitation mark is formed on the second surface portion 12.

Next, the molten resin is solidified and cooled by heat conduction with the mold. The hollow portion 14 is held at a predetermined pressure until it is solidified and cooled (step S207). By holding the pressure, the first surface portion 11 is pressed against the first region 311, so that the surface transfer property of the first surface portion 11 can be improved. Next, the compressed gas in the hollow portion 14 is removed, the mold is opened, and the fθ mirror (resin molded product) 10 is taken out (step S208).

The injection molding machine according to the modification of the first embodiment includes the detection unit 33 and the timer 39, and when the determination unit 37 determines that the detected temperature t1 from the detection unit 33 exceeds the reference temperature t0, the determination is performed. The elapsed time from the time is measured by the timer 39, and the control means 35 controls the filling means 32 and the gas injection means 34 based on the measurement result.

Next, a manufacturing apparatus according to another modification of the first embodiment will be described with reference to FIG. FIG. 11 is a functional block diagram of an injection molding machine provided with a timer 39. Upon receiving the elapsed time measured by the timer 39, the control means 35 controls the filling means 32 to stop the resin filling, and controls the gas injection means 34 to start the injection of the compressed gas.

In the injection molding machine according to this modification, the control means 35 controls the filling means 32 and the gas injection means 34 when the elapsed time from the start of resin filling exceeds a predetermined time. . As a result, the hesitation mark HM can be formed on the second surface portion 12.

Resin filling may be started when a screw (not shown) of the filling means 32 is started, or when the control means 35 instructs the filling means 32 to start filling. The timer 39 measures the elapsed time. The determination unit 37 determines whether the measured elapsed time has exceeded a predetermined time. In response to the determination by the determination means 37 that the elapsed time has exceeded a predetermined time, the control means 35 controls the filling means 32 and the gas injection means 34. Since the detection means 33 such as a temperature sensor is not required, the cost can be reduced.

Next, a method for manufacturing the base material of the fθ mirror 10 according to another modification will be described with reference to FIG. FIG. 12 is a flowchart showing a manufacturing process of the base material of the fθ mirror 10.

The control means 35 controls the filling means 32, rotates the screw, injects the molten resin from the nozzle 324, passes through the spool 323, the runner 322, and the gate 321 and fills the cavity 31 (step S301). .

Timer 39 measures the elapsed time from the start of resin filling (step S302). Further, the cavity 31 is filled with molten resin. The determination unit 37 determines whether the measured elapsed time has exceeded a predetermined time. When the determination means 37 determines that the measured elapsed time has exceeded a predetermined time (step S303; Y), the control means 35 controls the filling means 32 to stop filling the cavity 31 with resin. (Step S304). Next, the control means 35 controls the gas injection means 34 to open the electromagnetic valve 341. Thereby, the compressed gas in the tank (not shown) is ejected from the injection port portion 342 into the cavity 31. At this time, the front end portion of the molten resin reaches the second surface portion 12.

The injection port portion 342 is disposed on the bottom surface 313 facing the second region 312, and the injection port portion 342 is opened in the longitudinal direction, whereby compressed gas is filled in the longitudinal direction in the filled resin. Is injected (step S305). Thereby, the hollow part 14 extended in the elongate direction can be formed in resin. Further, when the determination unit 37 determines that the measured elapsed time has exceeded a predetermined time (when the tip of the molten resin reaches the second surface portion 12), the control unit 35 fills the resin. Since the compressed gas is injected into the resin, hesitation marks are formed on the second surface portion 12.

Next, the molten resin is solidified and cooled by heat conduction with the mold. The hollow portion 14 is maintained at a predetermined pressure until it is solidified and cooled (step S306). By holding the pressure, the first surface portion 11 is pressed against the first region 311, so that the surface transfer property of the first surface portion 11 can be improved. Next, the compressed gas in the hollow portion 14 is removed, the mold is opened, and the fθ mirror (resin molded product) 10 is taken out (step S307).
[Second Embodiment]
Next, a resin molded product for an optical element according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 13 is a plan view of a resin molded product for optical elements, and FIG. 14 is a cross-sectional view of the resin molded product for optical elements. The resin molded product for the optical element according to the first embodiment has been described by using the fθ mirror 10 as a representative. However, the resin molded product for the optical element according to the second embodiment by using the fθ lens 20 as a representative. To do.

The fθ lens 20 is provided in the laser beam scanning optical device in the same manner as the fθ mirror 10. The fθ mirror 10 has a mirror surface portion 13 that reflects a laser beam, whereas the fθ lens 20 has an optical surface portion 23 that transmits a laser beam. The fθ lens 20 having the optical surface portion 23 also has the same function as the fθ mirror 10, and the laser beam deflected at a constant angular velocity by the polygon mirror 3 is made constant on the scanning surface (on the photosensitive drum 7). Change the speed so that This laser beam is a gallium nitride based semiconductor laser and has an oscillation wavelength of 408 nm.

The fθ lens 20 is formed in a long plate shape, has a predetermined range H2 in the longitudinal direction, and is provided with an optical surface portion 23 that transmits a light beam received within the predetermined range H2. And a second surface portion 22 disposed around the first surface portion 21 and a hollow portion 24 provided therein. The first surface portion 21 is provided on each of the upper surface side and the lower surface side in the paper surface of FIG. The first surface portion 21 on the upper surface side is a convex surface having a predetermined curved surface shape in the short direction. The first surface portion 21 on the lower surface side is a concave surface having a predetermined curved surface shape in the short direction.

In the width in the longitudinal direction, the predetermined range is set to be equal to or less than the area of the optical surface portion 23, and the area of the optical surface portion 23 is set to be equal to or less than the area of the first surface portion 21. In addition, the area | region of the optical surface part 23 and the area | region of the 1st surface part 21 matched by the width | variety of the elongate direction are shown in FIG.

In FIG. 13, R1 represents the range of the first surface portion 21 in the short direction, and R2 represents the range of the second surface portion 22 in the short direction.

In the fθ lens 20, a long plate-like base material, an optical surface portion 23 positioned on the upper surface side and the lower surface side of the base material, and the optical surface portion 23 are positioned in the base material along the optical surface portion 23 in the longitudinal direction. And the length of the hollow portion 24 in the longitudinal direction is longer than the length of the optical surface portion 23 in the longitudinal direction, and both ends of the hollow portion 14 are connected to both ends of the optical surface portion 23 in the longitudinal direction. By forming it on the outer side, it is released to the hollow portion 24 in which the tensile stress generated by the shrinkage accompanying the curing of the resin is formed. Accuracy is improved.

In the resin molded product of this embodiment, the length in the longitudinal direction of the optical surface portion 23 is L1, the length in the short direction is W1, the length in the long direction of the hollow portion 24 is L2, and the length in the short direction is W2. When the length in the short direction of the base material is W4 and the distance from the end of the optical surface portion 23 to the end of the base material is L5 with respect to one side in the long direction, it is hollow from the end of the optical surface portion 23 with respect to one side in the long direction. The distance L3 to the end of the portion 24 is 0 ≦ L3 <L5, and the distance W3 from the end of the optical surface portion 23 to the end of the hollow portion 24 with respect to one side in the short direction satisfies 0 ≦ W3 <W2 / 2. More preferably.

Also, the relationship between the length W1 of the optical surface portion 23 and the length W2 of the hollow portion 24 in the short direction is preferably 0.01 ≦ W2 / W1 ≦ 1.

Further, the fθ lens 20 includes a first molding portion 25 including the first surface portion 21 as a surface thereof, and a second molding portion including the second surface portion 22 as a surface thereof and surrounding the first molding portion 25 in a frame shape. 26. The second molding part 26 has a rib 27 and an end frame part 28. The ribs 27 are thicker than the first molding part 25 and are formed on both sides of the first molding part 25 in the short direction perpendicular to the long direction along the long direction. Further, the end frame portion 28 is formed at both ends of the first molding portion 25 so as to be continuous with the first molding portion 25 with substantially the same thickness as the first molding portion 25. Therefore, the 2nd surface part 22 distribute | arranged to the circumference | surroundings of the 1st surface part 21 is the end frame part distribute | arranged to the surface (upper surface and lower surface) of the rib 27, and the both sides of the 1st surface portion 21 in the elongate direction. 28 surfaces (upper and lower surfaces).

It is possible to improve the overall rigidity of the fθ lens 20 by providing the ribs 27 along the first surface portion 21. In addition, since the rib 27 is provided along the first surface portion 21, the shape of the rib 27 can be determined without being restricted by the shape of the first molded portion 25, etc. Can be increased. Thereby, the rib 27 can be formed into a shape that facilitates the formation of the hollow portion 24 with, for example, a predetermined thickness and a predetermined width in the short direction. Furthermore, since the rib 27 is linearly formed in the longitudinal direction and the hollow portion 24 is also linearly formed in the longitudinal direction, the hollow portion 24 is easily formed.

Furthermore, by providing the hollow portion 24 inside the rib 27, the warpage of the rib 27 can be reduced, and the warpage of the first molding portion 25 can also be reduced, whereby the first It becomes possible to prevent the surface accuracy of the optical surface portion 23 provided on the first surface portion 21 of the molding portion 25 from being lowered.

The hesitation mark HM is formed on the surface of the rib 27 and the surface of the end frame portion 28 which are the second surface portion 22. Also in the second embodiment, since the hesitation mark HM is formed on the second surface portion 22, it is possible to prevent the appearance abnormality of the first surface portion 21 on which the optical surface portion 23 is provided.

Next, an injection molding machine for manufacturing the base material of the fθ lens 20 will be described. The basic configuration of this injection molding machine is the same as that of the above-described injection molding machine of the fθ mirror 10, and the description thereof is omitted. Hereinafter, different configurations will be described.
(Detection means)
The one or more detection means 33 are desirably arranged on the inner surface of the cavity 31 for forming the end frame portion 28. By disposing the detection means 33 at this position, it is possible to directly detect the tip portion of the molten resin that exceeds the first surface portion 21, and the hesitation mark HM can be reliably detected by the second surface portion 22 (end frame portion). 28 surface). Furthermore, the reliability of forming the hesitation mark HM on the second surface portion 22 can be increased by arranging the plurality of detection means 33 at the above positions. The detection means 33 is arranged on the inner surface of the cavity 31 (the inner surface of the cavity 31 for forming the rib 27) having the same range as the inner surface of the cavity 31 for forming the end frame portion 28. May be.

Further, the detection means 33 is arranged on the inner surface of the cavity 31 (the inner surface of the cavity 31 for forming the rib 27) having the same range as the inner surface of the cavity 31 for forming the first surface portion 21. May be. In this case, when the determination unit 37 determines that the detected temperature t1 from the detection unit 33 exceeds the reference temperature t0, the control unit 35 causes the timer 39 to measure the elapsed time since the determination, and the elapsed time is determined in advance. The filling means 32 and the gas injection means 34 are controlled in response to the judgment of the judgment means 37 that the predetermined time has been exceeded.
(Material of fθ lens)
Next, materials for the fθ lens 20 will be described. Examples of the resin material constituting the base material of the fθ lens 20 include polycarbonate, polyethylene terephthalate, polymethyl methacrylate, cycloolefin polymer, or a resin composed of two or more of these. In the fθ mirror 10, it is preferable to use a polycarbonate or a cycloolefin polymer.
(Production method)
The base material of the fθ lens 20 is manufactured by the above manufacturing apparatus and materials. Since the manufacturing method of the fθ lens 20 is basically the same as the manufacturing method according to the first embodiment, the description thereof is omitted.

In addition, in the said embodiment, although the resin molded product for optical elements was demonstrated, it is not restricted to the resin molded product for optical elements. For example, when a hollow portion is provided inside and has a surface with a predetermined surface accuracy and a surface lower than the predetermined surface accuracy, it is applied to a resin molded product that forms a hesitation mark on a plane lower than the predetermined surface accuracy. It goes without saying that it is possible.

Hereinafter, the present invention will be described based on preferred embodiments. In the embodiment, the resin molded product to be manufactured is a base material of the fθ mirror 10. Similarly, the comparative example is the base material of the fθ mirror 10.

The fθ mirror 10 was molded and manufactured using the following two patterns of molds with the cavity shape as shown in FIG. 3 using the manufacturing apparatus and manufacturing method described above.

(Pattern 1)
A = B = 5.0mm
When two fθ mirrors obtained by such molding were evaluated, it was confirmed that a mirror shape with high surface accuracy in which shape deterioration due to sink marks or the like was suppressed over the entire first surface portion was obtained.

In addition, it was confirmed that by using the mirror in a scanning optical device using a laser beam having a wavelength of 408 nm, the spot was sufficiently narrowed and high-definition image formation could be performed.

(Pattern 2)
On the other hand, as a comparative example, an fθ mirror was formed and manufactured in the same manner using a cavity-shaped mold in which the first surface portion and the end of the optical element coincided. In addition, it was found that some of the shapes were deteriorated due to sink marks, and satisfactory image formation could not be performed in the above-described scanning optical apparatus.

HM hesitation mark t1 detection temperature t0 reference temperature 10 fθ mirror 11 first surface portion 12 second surface portion 13 mirror surface portion 14 hollow portion 20 fθ lens 21 first surface portion 22 second surface portion 23 optical surface portion 24 hollow portion 25 first Molding part 26 Second molding part 27 Rib 28 End frame part 31 Cavity 32 Filling means 33 Detection means 34 Gas injection means 35 Control means 36 Storage means 37 Judgment means 38 Interface 39 Timer 41 Operation means 42 Mold 311 First region 312 First 2 region 313 Bottom surface 314 Side wall surface 315 Mirror surface forming part 341 Solenoid valve 342 Injection port part

Claims

A resin molded product for an optical element having a first surface portion on a part of a surface of a base material molded from a resin and having a hollow portion formed by injecting a fluid from the outside into the base material. ,
A distance between the first end of the base and the end of the first surface near the first end is A, and the end is different from the first end of the base. When the distance between the second end portion on the opposite side through the first surface portion and the end portion of the first surface portion on the side close to the second end portion is B, the following relationship is established: A resin molded product for optical elements characterized by satisfying.
A> 0
B> 0
A ≦ B
The resin molded product for an optical element according to claim 1, wherein the surface roughness Ra of the entire first surface portion is Ra ≦ 5 (nm).
A resin molded product for an optical element, wherein a mirror surface portion is formed on the first surface portion of the resin molded product for an optical element according to claim 1.
A light source, a deflecting means for deflecting the light emitted from the light source, a condensing means for allowing the light emitted from the light source to enter and condensing on the deflecting means, and the light deflected by the deflecting means on the surface to be scanned A scanning optical device having an imaging optical system for imaging,
At least one optical element of the optical elements constituting the imaging optical system has one surface portion on a part of the surface of a long base material formed of resin, and fluid is supplied to the inside of the base material from the outside. An optical element having a hollow portion formed by injection, wherein the distance between the first end portion of the substrate and the end portion of the first surface portion on the side close to the first end portion is A, A second end portion that is different from the first end portion of the substrate and is opposite to the second end portion through the first surface portion, and the first surface portion on the side close to the second end portion. A scanning optical device characterized by satisfying the following relationship, where B is the distance from the end of:
A> 0
B> 0
A ≦ B
5. The scanning optical apparatus according to claim 4, wherein a surface roughness Ra of the entire first surface portion is Ra ≦ 5 (nm).
6. The scanning optical device according to claim 4, wherein a mirror surface portion that reflects incident light is formed on the first surface portion.
The scanning optical device according to claim 6, wherein a surface roughness Ra of the mirror surface portion is Ra ≦ 5 (nm).
A resin molded product for an optical element having a first surface portion on a part of a surface of a base material molded from a resin and having a hollow portion formed by injecting a fluid from the outside into the base material. ,
A distance between the first end of the base and the end of the first surface near the first end is A, and the end is different from the first end of the base. When the distance between the second end portion on the opposite side through the first surface portion and the end portion of the first surface portion on the side close to the second end portion is B, the following relationship A > 0
B> 0
A ≦ B
A method for producing a resin molded product for an optical element satisfying
A first mold having a transfer surface for transferring the first surface portion; and a second mold that is provided opposite to the first mold, and that forms a cavity by clamping between the first mold and the first mold. Preparing the mold, and
An injection step of injecting a molten resin from one side of the cavity end into the cavity;
A detection step of detecting that the tip portion of the resin filled by the injection step is in a predetermined position;
Controlling the filling of the filled resin based on the detection of the detection step, and injecting a fluid into the cavity to form a hollow portion therein;
A method for producing a resin molded product for an optical element, comprising:
The method for producing a resin molded product for an optical element according to claim 8, wherein the surface roughness Ra of the first surface portion is Ra ≦ 5.
The resin molding for optical elements according to claim 8, further comprising: a mirror surface portion forming step of forming a mirror surface portion on the first surface portion of the resin molded product obtained after the fluid injection step. Product manufacturing method.
The method for producing a resin molded product for an optical element according to any one of claims 8 to 10, wherein in the fluid injection step, the injection of the fluid is started after a lapse of a predetermined time after stopping the resin filling. .
A resin molded product for an optical element having a first surface portion on a part of a surface of a base material molded from a resin and having a hollow portion formed by injecting a fluid from the outside into the base material. ,
A distance between the first end of the base and the end of the first surface near the first end is A, and the end is different from the first end of the base. When the distance between the second end portion on the opposite side through the first surface portion and the end portion of the first surface portion on the side close to the second end portion is B, the following relationship A > 0
B> 0
A ≦ B
An apparatus for manufacturing a resin molded product for an optical element satisfying
A first mold having a transfer surface for transferring the first surface portion;
A second mold which is provided opposite to the first mold and forms a cavity by clamping between the first mold and the first mold;
Filling means for injecting a molten resin material into the cavity from one side of the cavity end;
Detecting means for detecting that the resin filled in the cavity by the filling means is in a predetermined position;
Fluid injecting means for injecting fluid into the cavity to form a hollow portion therein;
Control means for controlling the filling of the resin by the filling means based on the detection result that the resin is filled in a predetermined position by the detecting means, and for controlling the injection of the fluid into the cavity by the fluid injecting means; ,
An apparatus for producing a resin molded product for an optical element.